The present invention relates to electrical connectors. More particularly, the present invention is directed to a fiber optic interconnect system that utilizes alignment chips to position a plurality of stacked ferrules in order to align optical fiber arrays.
As fiber optic waveguides overtake copper transmission wires as the preferred method of transmitting information, the methods and systems for interconnecting fiber waveguides continue to evolve. Glass fiber interconnection techniques are significantly more demanding than copper wire connectors due in part to the requirement that glass fibers must be connected end to end, and connected with a precision sufficient to exactly align very small fiber waveguide cores to within a few microns, and often within a fraction of a micron. Because fiber waveguides are capable of carrying enormous quantities of information as compared to copper wires, typically, only a relatively few number of fibers are required to match or even exceed the capacity of large bundles of wires in copper cables. However, with the increasing capacity demanded by current and future data and multimedia transmission networks, the number of fibers in a single transmission cable continues to grow.
The end-to-end high precision connection requirement of fiber waveguides precludes simply bundling of large numbers of individual fibers in a cable as was the practice with copper wires. Instead the fibers are organized in a high precision, fixed, spatial relation. A common approach for such arrays are ribbon cables in which a plurality of fibers are organized and molded side by side in a plastic ribbon. Alignment of optical fiber arrays either with other arrays or with optical components is troublesome, especially for the case of single mode fibers which have an extremely small core diameter (typically approximately 9 xcexcm). A typical connector for fiber arrays includes two ferrules or plugs of silicon with grooves formed therein for accommodating the fibers (e.g., 18 optical fibers). Each plug is formed from two mated members which are bonded together to encase the fibers. The grooves are formed prior to bonding by anisotropically etching a major surface of each member in an array corresponding to the fibers so that when the members are bonded, each fiber lies in a groove which is precisely aligned with all other fibers in the array. However, while the fibers within a plug may be fairly closely aligned with each other, a problem exists in aligning these fibers with another fiber array or with an array of optical components.
While ribbon connectors are capable of very high transmission capacities there is a need for even greater capacity. An approach for addressing this is to stack fiber waveguide ribbons. The interconnection for such stacked arrays requires a similarly stacked connector, which presents new problems in precisely aligning the fiber waveguides in the added or stacking dimension. Typically, an alignment member is provided between the stacked ribbons in order to maintain fiber-to-fiber alignment. However, this approach increases the size of the connector because of the space required for the alignment member. This approach also increases the number and complexity of interconnecting elements between complementary connectors, as several alignment members must mate as the connectors are joined. While this structure is known, precision alignment of fibers remains an issue, especially as the size and complexity of the connectors grows.
It would, therefore, be desirable to reduce the space required by the optical fiber connector, while also increasing the density of connection points. There is also a need for a high density optical fiber connector that provides for improved precision in the alignment of the fibers, while also reducing the fiber-to-fiber distance. The present invention provides such a solution.
In accordance with an aspect of the present invention, there is provided an optical connector that includes alignment chips provided on opposing sides of the connector, a ferrule mounted between the alignment chips and alignment pins.
In accordance with a feature of the invention, the optical connector further includes a housing, and the alignment chips, the alignment pins and the ferrule are contained withing the housing. The housing may include generally parallel ribs and the alignment chips may include generally parallel grooves that cooperate with the ribs to secure the alignment chips within the housing. The ribs may have a cross-sectional shape of a truncated cone.
In accordance with another feature, each of the alignment chips has a ridge formed on a wall thereof, and the ferrule has v-grooves provided on opposing ends thereof that cooperate with the ridges to position the ferrule within the connector. Also, the alignment chips may include a plurality of regularly spaced ridges such that a plurality of ferrules may be aligned within the connector. The alignment chips may be made of silicon and the ridge may be formed having a cross-sectional shape of a truncated cone.
In accordance with yet another feature, the ferrule comprises two like silicon members, each of the like members having v-grooves etched therein to position a plurality of optical fibers. The like members each have angled edges that form the ferrules v-grooves.
In accordance with still another feature, the alignment pins position the connector with respect to a complementary connector when mated thereto. The alignment pins may be positioned in planes generally parallel to the ferrule and fabricated as a section of a cylinder such that edges of the alignment pins have a circular arc.
In accordance with another aspect of the invention, there is provided a multiple array optical connector that includes an outer housing, a pair of generally parallel alignment chips provided on opposing inside surfaces of the outer housing, a plurality of ferrules mounted in perpendicular planes to the pair of alignment chips, and alignment pins provided at opposing ends of the pair of alignment chips.
In accordance with a feature of the invention, the housing includes generally parallel ribs and each of the pair of alignment chips includes generally parallel grooves that cooperate with the generally parallel ribs to locate the pair alignment chips in the housing.
In accordance with another feature, each of the alignment chips includes a plurality of regularly spaced ridges, and each of the plurality of ferrules includes grooves provided on opposing ends thereof that cooperate with the ridges to position the plurality of ferrules within the connector.
In accordance with yet another aspect of the invention, there is provided a connector for connecting multiple arrays of optical fibers arranged in generally parallel planes. The connector includes a plurality of ferrules each containing an array of optical fibers, alignment chips that position the plurality of ferrules within the connector, and alignment pins that position the connector with respect to a complementary connector.
In accordance with a feature of the invention, the ferrules and the alignment chips are made of silicon, and the ridges and the grooves are formed by an etching process.
In accordance with another feature of the invention, the alignment pins are positioned in planes generally parallel to the plurality of ferrules, and the alignment pins position the connector with respect to a complementary connector when mated thereto.
Other features will be described herein.